My father has depression and believes that he no longer has a purpose in life other than me and my brother. A lot of bad stuff has happened to him, including losing a sister to cancer. Whenever he witnesses my mum treating me that way he defends me the best he can, but that only causes her to turn on him and confront me later to accuse me of ganging up on her. What's more, he refuses to seek help for his depression because he believes no amount of counselling could aid him, and the only time he did seek therapy the therapist was no help and blamed the depression on the few areas of his life he was happy in. He really does do all he can, and if there was a way for him to stop my mother he would. She just doesn't listen to either of us. As for where he lives, he and my mother are still together, though he considers breaking up with her when I go to university. Seriously though I'm not at all ashamed of him, he is the most considerate person I know and does what he can.

So in other words, both of your parents are unwell. Since your father suffers from depression, he is already dealing with a lot. That was an important detail.

All that I can say is that you need to take care of yourself which probably includes going to some type for therapy or counselling by yourself to learn how to handle your parents. Encourage your father to come with you. The better your understanding is of your mother's illness the easier it will be to deal with. Plz don't reply by saying that you don't know where to go or can't afford it. If you saw this as a serious situation you would try to make something happen through your school and/or a social worker of some sort.